Winter 2017-18 Professional MET Winter Forecasts/thoughts

[ChescoWx]

Some updated Winter Forecast thoughts from this AM from the WeatherBell Team

"In terms of the past five winters for the nation as a whole, this should be a more widespread winter. I think there will be periods of shifting, as to where the worst of winter will be. The forecast balances out two dangers: (1) that the 1995-96 example tries to run the table and (2) if the MJO is amped-up and goes into the cold phases, it could get really ugly given there will be an opportunity to put snow down.

The other winters are when major warmups beat back the overall cold. My strategy from the get-go is to let you know this is not some ho-hum winter. A lot of forecasts issued after our first one back in summer seem to echo what we have been saying. That being said, I had my suspicions on the modeling having to shift eastward for the early winter, so I am jumping on that. I fear the threat of a mid-winter warm up. The analogs I showed you had the warm October, the cold trying to get into the East early, but also have a pull back. So the result is more cold farther to the east because of the early cold and then try to home in as we see some of the other things I just talked about. This winter has a lot of potential and certainly the way we get to the end is likely to be a heck of ride."

Overall they show near normal temps and above normal snowfall....but with a cold period between now and Christmas and then a warm up in January before winter returns in February.

[ChescoWx]

Final winter write up from Weatherbell Team - long read but interesting. They have very consistent with their forecast and so far it has been right on target...let's see how they do the rest of the winter - enjoy!

We are going to the idea that January will not have a huge warm up (or put it this way, if it comes it will have to fight off the cold in the opening of the month).

The forecast we have had out stressed this winter would be a wild ride. Our analog packages, including the WeatherBELL Pioneer model, have been colder in the East. The Pioneer model was excellent in the cold winters of 2013-14 and 2014-15, but while doing a good job in the middle atmosphere over the past two winters, its low-level temperature response was not good. However, this year colder weather is on the table, and the pattern is going toward our analogs.

There is still a worry that there will be a very warm mid or late winter period, with the return of cold later on. We have low solar activity and an easterly QBO, which favor an enhanced MJO. Should it go into the warm phases like it did in 2005-06 or last winter in January, an entire winter forecast can be blown to the four winds. That being said, there are years it went the other way.

Another year sticking out, though not in the hurricane activity and La Niña analog package I have been using (see below), is 1981-82. The last two winters have seen warm outduel cold. It appears this winter there is a good chance that cold can at least fight it to a draw and perhaps wind up hitting and holding. The big problem is the idea that this will now feedback on itself through mid and late December with increased snow cover until the pattern grows so severe, it then does "snap" back to warmer. Before any snap can occur, it would get extremely cold.

The current analog package incorporates all the La Niña and active hurricane season analogs I have been writing about (and have not used since 2010). My error in 2010 was that the cold was longer and stronger - I correctly forecasted a flip to a positive AO in mid-winter, but it made little difference as winter kept coming. That idea is on the table since 2010 is a strong analog, along with 1995 and 1950 (they are double-weighted). However, so are years like 1998-99 and 1999-00, which had similar active Atlantic hurricanes and low activity in the western Pacific but also had warmer water in Nino1+2 (eastern Pacific) versus Nino3.4 (central Pacific). That La Niña was also much stronger. The weaker La Niñas tend to be colder for the U.S. if Nino1+2 is as cold or colder (and it looks that way this winter).

As a side note, it is fascinating to look at the Atlantic hurricane seasons of 1933, 1995 and 2005 independent of any other idea. All were highly active years and all had very cold Decembers. Two of them, 1933-34 and 2005-06 had blow torch Januarys followed by winter's return later. Even 1996 backed the core of the cold to the west in January, but then it came back eastward later.

Interestingly enough the Pioneer model does not incorporate the factors that I have been showing with the hurricane season, but of course the La Niña is a big deal. The hurricane season theory is rather simple - the distribution of the global hurricane activity is due to a certain overall global pattern. When Nino1+2 is as cold or colder than Nino3.4 it favors early cold in the eastern U.S.

Recently a forecast appeared based on Siberian Snowfall that essentially mimicked our idea that has been out. This was encouraging because it meant another method saw what we have been seeing from the Pioneer model and this different method I have been showing you (3 independent methodologies).

Over the last 2 weeks, temperatures have gone to the November analog!:

Us old guys were taught the "rubber band theory" where continued cold shots culminate in one major one, and then the atmosphere snaps the other way. An example of that was the 1989-90 winter and even 1976-77 (by the time that happened, December and January had been one of the most severe on record). That being said, the problem is that we have some big hitters like 2010-11, 1995-96 and 1981-82. Independent of each other, any one of those years would lead to stronger cold. So the call is to chill January some, still rely on some backing off for a time (not to the blowtorch of the past two years). If it doesn't then we are looking at an HDD season like 2013-14.

As for snowfall, I have not changed the snowfall forecast. The pattern should feature a jet stream cutting in from the west-northwest and buckling near the eastern seaboard early. It should then pull back, perhaps with plenty of fight between warm and cold. This volatility leads to precipitation and I do think even when areas of the nation are warm, cold will still be around to fight.

The Verdict

The forecast is colder. The danger I think remains it is not cold enough and that like 2010-11, warmth never really takes hold. My strategy is to make the overall emphasis on the front cold and then let you know there is a high stakes mid to late winter period.

[ChescoWx]

Latest from JB on twitter "Coldest last 10 days of year for US as a whole since 2000 likely on the way. EPO tanking again, and if it stays down so do temps WPO joing it!"